Fuse plug



March 23, 1937. KAUFFMAN 2,074,918

FUSE PLUG Original Filed A ri1 24, 19:55

Patented Mar. 23, 1937 UNITED STATES PATENT OFFICE FUSE PLUG Application April 24, 1935, Serial No. 18,038 Renewed February 6, 1937 Claims.

The present invention relates to fuse plugs adapted to be placed within the standard outout base of the conventional electric wiringsysterns whereby, should an overload or short circuit 5 occur in the wiring system, the fusible element will become blown or ruptured in order to break the electrical circuit.

The invention has amongst its primary objects to provide a one-piece casing for fuse plugs of this character which can be molded from glass,

porcelain, bakelite, or similar insulating materials and when so formed, the fusible element and contacts may be readily and easily applied thereto and connected for greatly reducing the manufacturing cost thereof and thereby rendering the same commercially desirable.

Another equally important object of the invention is to provide a one-piece molded casing for indicating fuse plugs having several compartmerits formed therein and which compartments are so separated as to permit an indicator to be placed within one compartment and a fusible element to be placed in another compartment of the casing whereby, the successful operation of the indicator will not in any manner be interfered with during the blowing of the fusible element.

Still a further object of the present invention is to provide a lamp indicator fuse comprising a casing formed in one piece of molded insulating material to which the usual electrical contacts may be attached having a vertical compartment for receiving a lamp indicator and another compartment spaced and separated from said vertical compartment for housing the fusible element.

Other objects of the invention will be in part obvious and in part pointed out hereinafter.

In order that the invention and its mode of operation may be readily understood by persons skilled in the art, I have in'the accompanying illustrative drawing and in the detailed following description based thereon, set out one possible embodiment of the same.

In this drawing:

Figure 1 is a vertical section through the fuse plug embodying the present invention;

Figure 2 is a vertical section through the molded one-piece casing of the fuse plug;

Figure 3 is a horizontal section taken on the line 3-3 of Figure 2 in the direction of the arrow points, and

Figure 4 is another horizontal section taken on the line 4-4 of Figure 2 in the direction of the arrow points. I

Referring now more particularly to the accompanying drawing, wherein like and corresponding parts are designated by similar reference characters throughout the several views, I have herein shown a plug fuse comprising a casing molded in a single piece of insulating material. This casing comprises a body portion I having a central bore extending vertically'therethrough and the upper end of this bore 2 being of greater diameter than the lower end 3 thereof. An annular cavity 4 is formed within the body portion of the casing and has an opening 5 which communicates with the section 3 of the vertical bore formed within the casing. Another opening 6 is formed within the body portion of the casing having one end connecting to the section 2 of the vertical bore and its outer end terminating with the outer face of the casing. An annular depression I may be formed in the upper end of the fuse casing in order to reduce the amount of material needed in molding the casing and further to provide a suitable space for the markings such as the name of the manufacturers, amperes and volts which are to be carried by the particular fuse of which this casing forms a part. The upper end of the fuse casing is provided with the usual serrations 8 and the outer sides of the casing have formed therewith threads 9.

From the construction herein set forth, it is quite obvious that a casing made in accordance with the present invention can be molded from porcelain, glass, bakelite, or similar insulating material and after it has been so molded, a central contact consisting of a brass rivet l0 may be inserted within the section 3 of the vertical bore formed within the casing and a conventional threaded contact shell i I may surround a portion of the casing and by engaging screw threads 9 formed with the casing, be retained thereon. A fusible element comprising a zinc strip I2 is posi- 40 tioned within the annular chamber or groove 4 of the casing which latter forms the fuse compartment of the fuse. One end iii of this fuse strip is positioned between the shell i l and the threads 9 and may be secured to the shell by solder or 45 other suitable fastening means. The opposite end of this fuse strip extends through the opening 5 and has a wedging engagement with the upper end of the rivet III. A glow lamp indicator l4 may be inserted within the upper section 2 of the 50 central bore formed within the body portion of the casing having one terminal or lead-in wire connected to the rivet l0, whereas, the opposite lead-in wire of this glow lamp extends along the side of the lamp adjacent the inner end of the 55 fastening these respective parts together. A resis- I tor l completely fills this opening 6 whereby it will form a connection between that terminal of the lamp I4 which is positioned adjacent the opening 6 and the upper end of the contact shell I I.

A fuse made in accordance with the above construction may be inserted within the sockets of the usual cut-out bases of electrical wiring systems and when so applied, the current will flow in the usual manner through the fuse link l2 but should an overload or short circuit occur in the wiring system, which would cause this fuse link to become blown or ruptured, a circuit would be established in which the lamp H is included, thereby causing the same to glow and give off a visible signal.

Should it become necessary to further seal the lamp compartment in order to prevent dust or lint entering the same and accumulating about the fuse link arranged therein, a cylindrical tube it of suitable insulating material may be placed Within the compartment in the manner as is illustrated in Figure l of the drawing.

Manifestly, the onstruction herein shown is capable of considerable modification and such modifications as come within the scope of my claims, I consider within the spirit of my invention.

I ciaim:-

i. A fuse plug comprising a casing molded in a single piece of insulating material having an axially arranged lamp compartment and a bore extending axially of the casing from the inner end of the lamp compartment, the outer end of said lamp compartment being opened, a central contact fitted into said bore through the outer end thereof, a threaded contact shell about said casing and together with the casing defining an annular chamber, a fusible element in said chamber connecting said contacts, a glow lamp adapted to be inserted through the outer opened end of said lamp compartment and rest within said lamp compartment, one terminal of said lamp being connected to the inner end of said central contact, said casing having a passage formed therein with its inner end communicating with said lamp compartment and its outer end covered by said shell, a resistor arranged within said recess and said resistor electrically connecting said threaded contact shell and the other terminal of said lamp.

2. A fuse plug comprising a casing having a lamp compartment and a fuse compartment spaced therefrom, a central contact rivet mounted within said casing and having one end extending within said fuse compartment, a threaded contact shell, a fusible element arranged within said fuse compartment, and being connected to said contact rivet and shell, a glow lamp arranged within said lamp compartment, one terminal of said lamp being connected to said contact rivet, said casing having a recess formed therein communieating with said lamp compartment, a plastic resistance composition completely filling said recess, the other terminal of said lamp being connected to one end of said resistance composition and the opposite end thereof contacting said threaded contact shell.

3. As an article of manufacture, a casing for fuse plugs consisting of a unitary body structure molded in a single piece of insulating material and having a centrally located bore extending through the longitudinal axis of said body, said body having an external annular recess formed therein about a portion of the bore and at one point being extended inwardly of the body and communicating with said centrally located bore, screw threads formed with the outer periphery of said body and said body having an opening formed therein in spaced relation to the recess and extending at right angles to and communicating with said centrally located bore.

4. As an article of manufacture, a fuse plug casing consisting of a body formed in a single piece of molded insulating material having a central opening extending therethrough, one end of said opening being of greater diameter than that of the remaining portion or end thereof for establishing a lamp compartment, said body having an annular recess formed in the outer periphery thereof communicating with said central opening, said body having a resistor retaining opening formed therein and extending at right angles to said central opening, one end of said resistor opening having communication with said central opening and its opposite or outer end communicating with the outer side of said body.

5. An indicator plug fuse comprising a casing molded in a single piece of insulating material having a central bore extending entirely through the longitudinal axis thereof, one end of said bore being of greater diameter than that of the opposite end thereof in order to provide a lamp compartment, a rivet mounted within said bore and providing a central contact for the fuse, said casing having an annular recess formed therein communicating with said centrally located bore, a threaded contact shell connected to said casing and closing the outer opened end of said annular recess, a fuse link positioned within said annular recess and electrically connecting said rivet with said threaded shell, a glow lamp positioned within said lamp compartment of said centrally located bore, said casing having a resistance element retaining opening formed therein extending at right angles to said central bore and communicating with the lamp compartment thereof, one terminal of said glow lamp being electrically connected to said rivet, the other terminal of said glow lamp extending within said resistance element retaining opening of the casing, a plastic resistance composition filling said resistance element retaining opening of the casing and said plastic resistance composition electrically conmeeting the terminal of the lamp extending within the resistance element retaining opening with said threaded contact shell.

LEROY A. KAUFFMAN. 

